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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #define LOG_TAG "MessageQueue-JNI"
     18 
     19 #include "JNIHelp.h"
     20 #include <android_runtime/AndroidRuntime.h>
     21 
     22 #include <utils/Looper.h>
     23 #include <utils/Log.h>
     24 #include "android_os_MessageQueue.h"
     25 
     26 namespace android {
     27 
     28 static struct {
     29     jfieldID mPtr;   // native object attached to the DVM MessageQueue
     30 } gMessageQueueClassInfo;
     31 
     32 
     33 class NativeMessageQueue : public MessageQueue {
     34 public:
     35     NativeMessageQueue();
     36     virtual ~NativeMessageQueue();
     37 
     38     virtual void raiseException(JNIEnv* env, const char* msg, jthrowable exceptionObj);
     39 
     40     void pollOnce(JNIEnv* env, int timeoutMillis);
     41 
     42     void wake();
     43 
     44 private:
     45     bool mInCallback;
     46     jthrowable mExceptionObj;
     47 };
     48 
     49 
     50 MessageQueue::MessageQueue() {
     51 }
     52 
     53 MessageQueue::~MessageQueue() {
     54 }
     55 
     56 bool MessageQueue::raiseAndClearException(JNIEnv* env, const char* msg) {
     57     jthrowable exceptionObj = env->ExceptionOccurred();
     58     if (exceptionObj) {
     59         env->ExceptionClear();
     60         raiseException(env, msg, exceptionObj);
     61         env->DeleteLocalRef(exceptionObj);
     62         return true;
     63     }
     64     return false;
     65 }
     66 
     67 NativeMessageQueue::NativeMessageQueue() : mInCallback(false), mExceptionObj(NULL) {
     68     mLooper = Looper::getForThread();
     69     if (mLooper == NULL) {
     70         mLooper = new Looper(false);
     71         Looper::setForThread(mLooper);
     72     }
     73 }
     74 
     75 NativeMessageQueue::~NativeMessageQueue() {
     76 }
     77 
     78 void NativeMessageQueue::raiseException(JNIEnv* env, const char* msg, jthrowable exceptionObj) {
     79     if (exceptionObj) {
     80         if (mInCallback) {
     81             if (mExceptionObj) {
     82                 env->DeleteLocalRef(mExceptionObj);
     83             }
     84             mExceptionObj = jthrowable(env->NewLocalRef(exceptionObj));
     85             ALOGE("Exception in MessageQueue callback: %s", msg);
     86             jniLogException(env, ANDROID_LOG_ERROR, LOG_TAG, exceptionObj);
     87         } else {
     88             ALOGE("Exception: %s", msg);
     89             jniLogException(env, ANDROID_LOG_ERROR, LOG_TAG, exceptionObj);
     90             LOG_ALWAYS_FATAL("raiseException() was called when not in a callback, exiting.");
     91         }
     92     }
     93 }
     94 
     95 void NativeMessageQueue::pollOnce(JNIEnv* env, int timeoutMillis) {
     96     mInCallback = true;
     97     mLooper->pollOnce(timeoutMillis);
     98     mInCallback = false;
     99     if (mExceptionObj) {
    100         env->Throw(mExceptionObj);
    101         env->DeleteLocalRef(mExceptionObj);
    102         mExceptionObj = NULL;
    103     }
    104 }
    105 
    106 void NativeMessageQueue::wake() {
    107     mLooper->wake();
    108 }
    109 
    110 // ----------------------------------------------------------------------------
    111 
    112 sp<MessageQueue> android_os_MessageQueue_getMessageQueue(JNIEnv* env, jobject messageQueueObj) {
    113     jint intPtr = env->GetIntField(messageQueueObj, gMessageQueueClassInfo.mPtr);
    114     return reinterpret_cast<NativeMessageQueue*>(intPtr);
    115 }
    116 
    117 static jint android_os_MessageQueue_nativeInit(JNIEnv* env, jclass clazz) {
    118     NativeMessageQueue* nativeMessageQueue = new NativeMessageQueue();
    119     if (!nativeMessageQueue) {
    120         jniThrowRuntimeException(env, "Unable to allocate native queue");
    121         return 0;
    122     }
    123 
    124     nativeMessageQueue->incStrong(env);
    125     return reinterpret_cast<jint>(nativeMessageQueue);
    126 }
    127 
    128 static void android_os_MessageQueue_nativeDestroy(JNIEnv* env, jclass clazz, jint ptr) {
    129     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
    130     nativeMessageQueue->decStrong(env);
    131 }
    132 
    133 static void android_os_MessageQueue_nativePollOnce(JNIEnv* env, jclass clazz,
    134         jint ptr, jint timeoutMillis) {
    135     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
    136     nativeMessageQueue->pollOnce(env, timeoutMillis);
    137 }
    138 
    139 static void android_os_MessageQueue_nativeWake(JNIEnv* env, jclass clazz, jint ptr) {
    140     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
    141     return nativeMessageQueue->wake();
    142 }
    143 
    144 static jboolean android_os_MessageQueue_nativeIsIdling(JNIEnv* env, jclass clazz, jint ptr) {
    145     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
    146     return nativeMessageQueue->getLooper()->isIdling();
    147 }
    148 
    149 // ----------------------------------------------------------------------------
    150 
    151 static JNINativeMethod gMessageQueueMethods[] = {
    152     /* name, signature, funcPtr */
    153     { "nativeInit", "()I", (void*)android_os_MessageQueue_nativeInit },
    154     { "nativeDestroy", "(I)V", (void*)android_os_MessageQueue_nativeDestroy },
    155     { "nativePollOnce", "(II)V", (void*)android_os_MessageQueue_nativePollOnce },
    156     { "nativeWake", "(I)V", (void*)android_os_MessageQueue_nativeWake },
    157     { "nativeIsIdling", "(I)Z", (void*)android_os_MessageQueue_nativeIsIdling }
    158 };
    159 
    160 #define FIND_CLASS(var, className) \
    161         var = env->FindClass(className); \
    162         LOG_FATAL_IF(! var, "Unable to find class " className);
    163 
    164 #define GET_FIELD_ID(var, clazz, fieldName, fieldDescriptor) \
    165         var = env->GetFieldID(clazz, fieldName, fieldDescriptor); \
    166         LOG_FATAL_IF(! var, "Unable to find field " fieldName);
    167 
    168 int register_android_os_MessageQueue(JNIEnv* env) {
    169     int res = jniRegisterNativeMethods(env, "android/os/MessageQueue",
    170             gMessageQueueMethods, NELEM(gMessageQueueMethods));
    171     LOG_FATAL_IF(res < 0, "Unable to register native methods.");
    172 
    173     jclass clazz;
    174     FIND_CLASS(clazz, "android/os/MessageQueue");
    175 
    176     GET_FIELD_ID(gMessageQueueClassInfo.mPtr, clazz,
    177             "mPtr", "I");
    178 
    179     return 0;
    180 }
    181 
    182 } // namespace android
    183